For one reason or another, the housing market has been on my mind recently, and in particular the various guesstimates of how much further house prices have to drop, or if they’ve already bottomed out, as some buyers might like to believe. Hence, as I have a tendency to do in these sort of situations, I decided to throw a load of numbers into an Excel spreadsheet and make my own attempt at empirically forecasting what “stable” house prices might look like, and how far we have to go until we get there. In doing this, I’ve focussed on the ratio of house prices to the country’s per capita GDP, and how this ratio has changed over the years. It would be reasonable to expect this ratio to be quite stable over time; the amount people are willing to pay for a property should be proportional to their earnings at the time.

Using house price data from The Department of The Environment, and indexed with GDP data from the CSO, I’ve put together the following graph of the ratio of house prices to GDP in Ireland since 1976 (click for full size):

The Department of the Environment provides two separate series of house prices, one for new houses and one for second hand houses. Over the past decade the price of new houses has been quite a lot lower than second hand houses, as new builds have primarily been apartments and small houses which would bring down the average. For this reason I’m going to focus on the prices of second hand houses (red line above), although I’ve included new houses (blue line) in the graph for completeness.

What’s immediately obvious from the graph is the house price bubble over the past decade, reaching a peak of over 9 times per capita GDP in 2006. There was also a similar bubble, although not nearly as pronounced, in the latter years of the 70s. In trying to gauge what a “stable” ratio might look like, it’s the inter-bubble years between these two that we should be looking at. As such, I would propose that a ratio of 6 or below be considered stable for the housing market. The ratio stayed below this level from 1985 to 1997, and, aside from a dip in the mid-90s, was pretty steady throughout. As can be clearly seen in the graph, if a ratio of 6 is stable, we’re still far from stable at the moment.

In order to estimate how much further house prices have to drop to get to a ratio of 6 times per capita GDP, I’ve worked on the assumption that both nominal house prices and GDP will bottom out at the end of 2010. I’ve used the ESRI’s projections of GDP for this year and the next in my calculations. After doing the sums, it seems that nominal second hand house prices will have to fall by a further 27.2% below Q2 2009 levels if they’re to reach a stable ratio to GDP by the end of next year. Of course, I’m using a ratio of 6 as an upper bound for stability; if the ratio was to reach as low as 4.91 (which it got to in 1995), then we could be looking at a drop of 40.4% in nominal prices instead.

This shouldn’t come as pleasant reading for anyone who has a vested interest in high property prices. Unfortunately, with the NAMA legislation now making its way through the Dáil, it won’t be long before we all have such a vested interest, which is becoming more worrying by the day.